Lilis Yuliati

Studi Numerik Pembakaran Butana (C4H10) dalam Meso Scale Combustor dengan Perforated Plate

This research was conducted to determine the combustion stability and flame temperature inside meso-scale combustor with variations of perforated plate flame holder and combustion gas temperature at combustor exit side using numerical method or Computational Fluid Dynamics (CFD). Meso-scale combustor is made of two pieces of quartz glass tube with a length of 20 mm and 10 mm. Each quartz glass tube having an internal diameter of 3.5 mm and a wall thickness of 0.7 mm. Two kinds of perforated plate flame holder made of copper i.e. perforated plate type I and perforated plate type II, inserted between two quartz glass tubes. Butane (C 4 H 10 ) and air were used in this study as fuel and oxidizer, respectively. Numerical simulations were performed using ANSYS Fluent 17.0. The result of numerical simulation showed that the most stable combustion is obtained in meso-scale combustor by using flame holder in the form of perforated plate type II at higher reactant velocity. In addition, the combustor with perforated plate flame holder type II also produces a higher flame temperature at the same reactant speed. These phenomena occured due to the temperature distribution into the reactans is more uniform and the recirculation heats into the reactans is better than the combustor with perforated plate flame holder type I. Flame and combustor walls temperatures increased with increasing recirculation heats.

Visualization of bubbles formation on the boiling process in tapering heat pipe with variation of evaporator to condenser diameter ratio

In the present study, a new tapering heat pipe design had been developed to enhance the thermal performances. Boiling visualization in the tapering heat pipe is investigated to provide the detailed information of bubbles nucleation. Experiment was conducted in the tapering heat pipe with variation of the evaporator (d) to condenser (D) diameter ratio. The values of d/D are varied at 1/1; 1/2; 1/3 and 1/4. Heat load was generated at the evaporator section using heater DC-Power supply at 30, 40 and 50 Watt. The visualization technique was developed by using a transparent glass tube and the images of boiling bubbles were captured by SLR camera. The glass tube inclination is 45 o and integrated with the NI-9211 and c-DAQ 9271 module. K-type thermocouple was set at the evaporator and condenser sections for measurement of boiling temperatures in the tapering heat pipe. Based on the results, it can be noted that variations of heat load and diameter ratio (d/D) of the evaporator and condenser affect the size and shape of boiling bubbles, as well as the nucleation temperature on the tapering heat pipe. The heat transfer coefficient tends to increase at a heat load of 50 W and diameter ratio d/D=1/4.

Performance Analysis of a Combined Blade Savonius Wind Turbines

The Savonius wind turbine has a lower performance than other types of wind turbines which may attract more study focus on this turbine. This study aimed to improve wind turbine performance by combining a conventional blade with an elliptical blade into a combined blade rotor. The analysis was performed on three blade models in computational fluid dynamics (CFD) using ANSYS_Fluent Release 14.5. Then the results were verified experimentally using an open wind tunnel system. The results of the numerical simulation were similar to the experimental and showed that the combined blade rotor has better dragging flow and overlap flow than the conventional and elliptical blade. Experimental verification showed that the combined blade was to increase the maximum coefficient of power (Cpmax.) by 11% of the conventional blade and to 5.5% of the elliptical blade.

Flame Stability Measurement on Rectangular Slot Meso-Scale Combustor

The biggest problem of combustion in the micro-scale or meso-scale combustor is heat loss. Heat loss led to a difficult of stable flame. This research aims to elucidate the flame stabilization and flammability limit of LPG-oxygen premixed flame, temperature distribution and flame visualization. Flame stabilization and flammability limit map are shows in φ - U plane. The result shows that there are six regions in the map that is stable without noise, stable with noise, transition zone, dead zone, pseudo stable, and blow off. Measurement parameters are LPG-oxygen flow velocity at various equivalent ratio and temperature. The flame stabilization and flammability limit map within measurement parameters are discussed.

Flammability Limit and Flame Visualization of Gaseous Fuel Combustion Inside Meso-scale Combustor with Different Thermal Conductivity

This study experimentally investigated effect of thermal conductivity on the combustioncharacteristics of gaseous fuel inside a meso-scale combustor. Combustion characteristics that wereobserved in this research include flame visualization and flammability limit. Quartz glass, stainlesssteel and copper tubes with inner diameters of 3.5 mm were used as combustors. Stainless steel wiremesh was inserted inside meso-scale combustor as a flame holder. Liquid petroleum gas (LPG),which is common fuel use by Indonesian people, was used as a gaseous fuel. A stable blue flame wasestablished inside meso-scale combustor at the downstream of wire mesh for all combustor withdifferent thermal conductivity. Furthermore, flame color is blue for combustion of fuel lean orstoichiometric mixture, and blue-green for combustion of fuel rich mixture. Meso-scale combustorwith the highest thermal conductivity has the narrowest flame cross section area, especially at lowerreactant velocity. Vice versa, this combustor has the widest flammability limit, mainly at the higherreactant velocity.